Elevator control device



June 16, 1936. J. RICE ELEVATOR CONTROL DEVICE Original Filed Jan. 13, 1930 in the operation of the drive mechanism for the- Patented June 16, 1936 UNETED STATES PATENT OFFICE ELEVATOR CONTROL DEVICE Original application January 13, 1930; Serial No.

Divided and this application March'- 21, 1934, Serial No. 716,600

5 Claims.

My invention relates to elevator control devices and more particularly to a drive mechanism for elevators and the like wherein the principal purpose of the invention is to improve the control elevator particularly in changes of speed of the elevator by the employment of an inertia controlling device.

This application is a division of my application Serial No. 420,511, filed January 13, 1938.

It is also a purpose of this invention to provide in combination with the cable drum for driving an elevator of an auxiliary braking device 00- operating with the motor drive braking device to create a drag on the machine and to assist the slowing of an elevator at a stop.

Other objects and advantages of the invention will appear as the description proceeds in connection with the accompanying drawing wherem Fig. 1 is a side view showing the cable drum of an elevator in combination with my improved control device;

Fig. 2 is a section on the line 2-2 of Fig. 1;

Fig. 3 is a reduced side view taken from the line 33 of Fig. 1.

Referring now in detail to the drawing, I show at 5 the usual cable sheave or drum over which the cables moving the elevator cars up and down the shaft operate. This drum is mounted on a suitable frame consisting of the base 6, standards 1 and 8, bearings 9 and i0, and drum shaft H. The shaft is driven from a suitable power device such as the motor l2, the shaft of which connects by means of worm and worm gear drive indicated at l3 to the shaft H on which the drum is mounted. The shaft 14 of the drive motor is provided with the usual braking drum l5 and brake shoes l6 for applying a braking effect to this shaft in stopping the elevator.

Braking in this fashion, however, subjects the drive shaft of the motor and the worm and gear drive to a terrific strain owing to the inertia of the cable drum and the car, so I have provided in addition to this braking device an auxiliary braking device which is particularly effective in bringing the car to a stop. This auxiliary braking device consists of an inertia controlling member comprising an auxiliary brake drum ll mounted on a suitable shaft l8 carried in the standard 1 and auxiliary standard l9 suitable bearings being provided. The drum I? has associated therewith the brake shoes 20 and 2| which are controlled by a small electric motor 22 through suitable gear mechanism, the details of Which are well known and form 'no part of the present invention. This auxiliary shaft l8 then is connected by means of the large gear 23 and pinion 24 to themain'drum -shaft ll sov as to rotate the auxiliary shaft l8= at a materiallyreduced speed 5 from the drum shaft II.

This in itself creates a drag at all times on the drum shaft which tends to avoid overrunning by the elevator and which also tends to slow down the elevator when the power is cut off from the drive motor and the brake applied to its shaft thus avoiding a certain amount of backlash which would occur if the inertia of the drum and elevator were not retarded in some fashion.

The brake shoes 2| when applied to the drum ll effect a powerful braking action on the drum shaft since their action on the slow moving drum H is communicated through the reduction gearing directly to the main drum shaft and give a smoother and greater braking power than would be obtained if these brake shoes were applied directly to the drum itself. This is because the drag of the slow speed gear 23 tends to brake the drum, and the slow speed of the brake drum and gear 23 tend to offset the momentum of the drum shaft. The force on the brake drum during a single revolution plus the friction losses in transmission is reduced in accordance with the gear ratio between gears 23 and 24 but the reduced force and friction loss is applied over a number of revolutions of the drum shaft. So for each turn of the brake drum the braking action is applied through several turns of the drum shaft.

This auxiliary braking device is found to be practically effective on push button type of elevators where the control of the braking is all automatic. Also the combination of the brake on the high speed shaft of the driving motor with the auxiliary braking device applied on a drum rotating at a much lower speed than that of the cable shaft gives an ideal combination in that we have braking effects applied to both a rotating element going faster than the cable shaft and a rotating element going slower than the cable shaft.

From the above description, it is thought that the construction and advantages of this device will be clear to those skilled in this art.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. An elevator drive mechanism including a drum shaft having a cable drum thereon, a higher speed shaft connected to said drum shaft, a lower speed shaft connected to said drum shaft, 55

and braking means on the higher and lower speed shafts said lower speed shaft being driven at a speed substantially less than the speed of said drum shaft.

2. An elevator drive mechanism including a drum shaft having a cable drum thereon, a higher speed shaft connected to said drum shaft, a lower speed shaftconnected to said drum shaft, and braking means on the higher and lower speed shafts one of the two last mentioned shafts driving the drum shaft and the other being driven therefrom.

3. An elevator drive mechanism including a drum shaft having a cable drum thereon, a higher speed shaft connected to said drum shaft, 2.

' lower speed shaft positively connected to said means for driving said higher speed shaft, a lower speed shaft, a reduction gearing positively connecting said lower speed shaft to the first named shaft to drive the lower speed shaft at a speed materially reduced from that of the first named shaft, and means on said lower speed shaft 00- operating with said gearing to create a drag on said first named shaft at all times.

5. In an elevator power unit, a cable drum, a shaft upon which drum is fixed, a higher speed shaft connected to said first named shaft, power means for driving said higher speed shaft, a lower speed shaft, a reduction gearing positively connecting said lower speed shaft to the first named shaft to drive the lower speed shaft at a speed materially reduced from that of the first named shaft, and means on said lower speed shaft cooperating with said gearing to create a drag on said first named shaft at all times, said means comprising a brake drum on said lower speed shaft, and brake shoes engageable with said brake drum to apply a braking force to the first named shaft through said gearing.

JOSEPH RICE. 

